e-mail is an important means of communication in the PDC (Personal Digital Cellular), GSM (Global System for Mobile Communications), or WCDMA (Wideband Code Division Multiple Access), CDMA20001X (Code Division Multiple Access 2000X), and other 3G (3rd Generation) mobile communication systems.
In protocol relating to e-mail, that is, TCP/IP (Transmission Control Protocol/Internet Protocol) specifications, a single user is bound to unique single addresses to create mail addresses. Further, it is also possible to bind addresses of a plurality of users to a unique single address to create mailing lists having the unique single address as a representative address.
A message sender can transmit a message to that address so as to deliver the message to the desired other party, more precisely the POP server with which the message receiver holds an account. Furthermore, at the time of transmission of the message, he or she can send the same message to a plurality of parties by designating a plurality of addresses.
When a mailing list has been created, it is possible to send a message to all members of the mailing list just by sending the message to the representative address assigned to the mailing list. The function of sending an e-mail to a mail address or mailing list is provided not only at computers and PDA's (Personal Digital Assistants) with an operating system, but also at mobile phones. Users can now send messages by e-mail without regard as to the time or location.
For example, if utilizing a mobile phone and utilizing a mailing list, it is possible to send a message relatively efficiently to a plurality of people without regard as to the time or location. Further, it is possible to send a message to members selected by inputting conditions to the mobile phone for extracting the members included on the mailing list.
However, when desiring to request to a plurality of members a job which just one or several of the members can perform, sometimes just having a mailing list is not enough.
For example, assume that all family members including a user X are made members of a mailing list. Sometimes the user X at home would like someone in the family returning home from the nearest train station, that is, one of the members of the mailing list, to make a purchase at a store on route from the nearest train station to home. If mailing all members on the mailing list, it becomes necessary for all members to communicate in order to decide who should make the purchase. If insufficiently communicating with each other, the same item may be purchased several times. Further, everyone might assume someone else would do the job and no one would make the purchase. Furthermore, even members in the mailing list definitely unable to make the purchase would also be sent the message resulting in wasted traffic. To avoid such wasted traffic, it is possible not to use the mailing list, but to send a message to each feasible member, but this would be inefficient.
As will be understood from this example, when it is sufficient for just one of a plurality of persons to accept an errand, it is impossible under the current setup to deal with the errand by sending a single message.
A communication system is known which prevents a user from passing by an electronic message board or a message addressed to the user without noticing it by identifying the user entering a predetermined area and performing a predetermined action with respect to the user to draw the user's attention to the message addressed to the user (see Patent Document 1).
[Patent Document 1] Japanese Laid-open Patent Publication No. 2005-253006